1. Field of the Disclosure
The present disclosure relates generally to a fluid flow regulator for regulating the initial flow rate of a fluid specimen. More particularly, the present disclosure relates to a variable fluid flow regulator that regulates the initial flow rate of blood into an evacuated blood collection device.
2. Description of the Related Art
Collapse of the patient's blood vessel during blood collection can occur as a result of a pressure differential created by the connection of the evacuated tube to the non-patient needle cannula. This collapse can occur as a result of the blood being removed too quickly from the patient's blood vessel. Physiological conditions such as the elasticity of the blood vessel wall can also contribute to this problem. With a standard evacuated tube, there is an instantaneous introduction of a sharp vacuum pressure when the evacuated tube is attached to the non-patient end of the blood collection device. This strong vacuum results in an initially high flow rate of blood out of the patient's blood vessel. This sharp outflow of blood coupled with the high elasticity of a patient's vessel can lead to the vessel wall being pulled down onto the bevel of the distal end of the patient cannula resulting in flow stoppage. The site for obtaining the blood supply can also be a contributing factor toward vessel collapse. Most typical blood collection sites are in the patient's arm and hand. Because of the one-way valves in the vessel, the supply of blood available for collection resides below the collection site. In-flow of new blood to this area is limited as a result of the capillary blood vessels. In the situations where there is little resident blood, such as a hand collection, the sharp vacuum from the collection tube leads to a high flow rate out of the vessel, which can lead to an outflow rate higher than the inflow rate and a rapid depletion of the resident blood. This scenario can quickly lead to collapse.
One way to avoid this collapse is to use a syringe for blood collection. Syringes can provide a user with greater control over the flow rate of blood out of the patient. The initial spike in pressure from an evacuated tube and the associated high flow rate can be avoided through the use of a syringe collection technique. However, the skill of the user plays a large role with this type of collection as there can be a lot of variability in the amount of force the user exerts on the syringe plunger and the associated flow rates. Also, if not used appropriately, the flow rates can be greater than a standard evacuated tube.
The manual flow regulator of the present invention seeks to minimize the incidence of vessel or vein collapse in patient populations susceptible to this type of condition. The device achieves this by controlling the flow rate of the blood out of the patient's vessel or vein. This is accomplished through the use of a variable flow resistor. The resistor acts to slow down the initial flow rate of blood into the evacuated tube and avoid the initial spike, as well as to slow down the overall collection time to avoid depleting the resident blood in the vessel too rapidly.